I will say this about the Sparki. They're liars.
They're claiming 24 hours off a single 16340 800mah battery.
That's a big, fat lie.
Personally, I wouldn't deal with a company that lied so blatantly on their website.

Also, they have some oddball connection, so you'll have to buy replacement atomizers and cartomizers from them.

I smell scam.

Edit: It's worse than I thought. They don't even use cartomizers. This thing uses the old obsolete atomizer/cartridge system that people stopped fooling with sometime about 2 years ago.
Don't even think about that P.O.S.

To answer your question about AA batteries. There are a couple small mods out there that people are making that use AA batteries. The problem is that they generally can't handle the current draw of a decent e-cig.
I've never seen a practical e-cig that takes AA batteries, and I've never seen one commercially available except ones that take a large 18650 sized battery pack consisting of a bunch of AA batteries.

If you're looking for something the size of an AA battery, the 14500 is the same size but in a lithium.

The 14650 in the e-Power is the same diameter as an AA, and about 1/2" longer. (15mm)

Ahhh.. That's too bad. That's a tough one. I don't know of any other reliable vendor that sell that model with the good switch. I'm sure there is one somewhere, but I don't know about it.

There are a lot of other PVs that take replaceable batteries, but not like an eGo style. I have one that I recommend very highly, but it's a bit more expensive and it doesn't come with any extras. OTOH, the vendor does ship internationally because another member from Australia (or are you in Austria?) got one just the other day. It takes a single 14500 battery, which is the same size as an AA. It's super high quality and will probably outlive you. I've run mine over with a truck, dropped it overboard in saltwater, buried it overnight in mud and dropped out a moving car window. And it still works like new. If you want something that's super high quality, it's the best. It's also small enough to hide in your palm or fit in any pocket. It's called the BB and here it is. It comes in black, silver vein and silver.AltSmoke.com | Personal Vaporizers | Electronic Cigarette | Ecigs | The BB - The BB - Starter Kits

Actually, that's not what they claim. They say it can last UP TO 24 hours. And that is technically true. It could even last more than a year, if you don't use it.

Like a disposable e-cig I got recently. They stated: up to 400 puffs (2 packs)! I got 140 out of it (14 cigs), but I can't say they lied to me. The "up to" covers them.

By the way, don't even think about using regular (disposable) AA's you can buy everywhere. They don't have the right voltage. PV's require 3.7 volt nominal, regular AA's are 1.5 volt, or something like 1.2 volt when they are rechargeable.

18650 batteries are where you want to be. Stay away from dual battery mods that use lithium ion batteries. Those are the most likely to experience differing voltage reverse charge meltdowns.

IMR batteries are safer than Li-ion batteries. The chemistry can take higher heat without failure and can deliver higher amperage without producing high heat. In an E-power you want one that uses IMR 18650 batts, IMO.

And I only smoked 6 a day for two years before that.
Provari and Sigelei Zmax V3 | CASAA Member

i use 6 AA 1.2v rechargeable batteries in my mod so don't disregard these batteries completely as they give a good vape. as for atomisers they are great if you know what you are doing. cartomisers are good for newbies.